MWL#182: Explain running statements: address review feedback

- Add Monty Program Ab copyright in new files
- Change Apc_target::make_apc_call() to accept a C++-style
  functor (instead of C-style function + parameter)

sql/my_apc.cc

 /*
-  TODO: MP AB Copyright
-*/
+   Copyright (c) 2009, 2011, Monty Program Ab
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; version 2 of the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
 
 
 #ifdef MY_APC_STANDALONE
@@ -139,8 +151,8 @@ void Apc_target::dequeue_request(Call_request *qe)
   to use thd->enter_cond() calls to be killable)
 */
 
-bool Apc_target::make_apc_call(apc_func_t func, void *func_arg, 
-                               int timeout_sec, bool *timed_out)
+bool Apc_target::make_apc_call(Apc_call *call, int timeout_sec, 
+                               bool *timed_out)
 {
   bool res= TRUE;
   *timed_out= FALSE;
@@ -149,8 +161,7 @@ bool Apc_target::make_apc_call(apc_func_t func, void *func_arg,
   {
     /* Create and post the request */
     Call_request apc_request;
-    apc_request.func= func;
-    apc_request.func_arg= func_arg;
+    apc_request.call= call;
     apc_request.processed= FALSE;
     mysql_cond_init(0 /* do not track in PS */, &apc_request.COND_request, NULL);
     enqueue_request(&apc_request);
@@ -229,7 +240,7 @@ void Apc_target::process_apc_requests()
     dequeue_request(request);
     request->processed= TRUE;
 
-    request->func(request->func_arg);
+    request->call->call_in_target_thread();
     request->what="func called by process_apc_requests";
 
 #ifndef DBUG_OFF

sql/my_apc.h

 /*
-  TODO: MP AB Copyright
-*/
+   Copyright (c) 2009, 2011, Monty Program Ab
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; version 2 of the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
 
 /*
   Interface
@@ -38,8 +50,12 @@ class Apc_target
   
   void process_apc_requests();
 
-  typedef void (*apc_func_t)(void *arg);
-  
+  class Apc_call
+  {
+  public:
+    virtual void call_in_target_thread()= 0;
+    virtual ~Apc_call() {}
+  };
   /*
     Make an APC call: schedule it for execution and wait until the target
     thread has executed it. This function must not be called from a thread
@@ -49,8 +65,7 @@ class Apc_target
     @retval TRUE  - Call wasnt made (either the target is in disabled state or
                     timeout occured)
   */
-  bool make_apc_call(apc_func_t func, void *func_arg, 
-                     int timeout_sec, bool *timed_out);
+  bool make_apc_call(Apc_call *call, int timeout_sec, bool *timed_out);
 
 #ifndef DBUG_OFF
   int n_calls_processed; /* Number of calls served by this target */
@@ -78,8 +93,7 @@ class Apc_target
   class Call_request
   {
   public:
-    apc_func_t func; /* Function to call */
-    void *func_arg;  /* Argument to pass it */
+    Apc_call *call; /* Functor to be called */
 
     /* The caller will actually wait for "processed==TRUE" */
     bool processed;

sql/sql_class.cc

@@ -3330,33 +3330,32 @@ void THD::restore_active_arena(Query_arena *set, Query_arena *backup)
   we're producing EXPLAIN for.
 */
 
-void Show_explain_request::get_explain_data(void *arg)
+void Show_explain_request::call_in_target_thread()
 {
-  Show_explain_request *req= (Show_explain_request*)arg;
   Query_arena backup_arena;
-  THD *target_thd= req->target_thd;
   bool printed_anything= FALSE;
 
   /* 
     Change the arena because JOIN::print_explain and co. are going to allocate
     items. Let them allocate them on our arena.
   */
-  target_thd->set_n_backup_active_arena((Query_arena*)req->request_thd,
+  target_thd->set_n_backup_active_arena((Query_arena*)request_thd,
                                         &backup_arena);
   
-  req->query_str.copy(target_thd->query(), 
-                      target_thd->query_length(),
-                      &my_charset_bin);
+  query_str.copy(target_thd->query(), 
+                 target_thd->query_length(),
+                 &my_charset_bin);
 
-  if (target_thd->lex->unit.print_explain(req->explain_buf, 0 /* explain flags*/,
+  if (target_thd->lex->unit.print_explain(explain_buf, 0 /* explain flags*/,
                                           &printed_anything))
-    req->failed_to_produce= TRUE;
+  {
+    failed_to_produce= TRUE;
+  }
 
   if (!printed_anything)
-    req->failed_to_produce= TRUE;
+    failed_to_produce= TRUE;
 
-  target_thd->restore_active_arena((Query_arena*)req->request_thd, 
-                                   &backup_arena);
+  target_thd->restore_active_arena((Query_arena*)request_thd, &backup_arena);
 }
 
 

sql/sql_class.h

@@ -1528,11 +1528,11 @@ class select_result_explain_buffer;
   
   The thread that runs SHOW EXPLAIN statement creates a Show_explain_request
   object R, and then schedules APC call of
-  Show_explain_request::get_explain_data((void*)&R).
+  Show_explain_request::call((void*)&R).
 
 */
 
-class Show_explain_request
+class Show_explain_request : public Apc_target::Apc_call
 {
 public:
   THD *target_thd;  /* thd that we're running SHOW EXPLAIN for */
@@ -1546,8 +1546,9 @@ class Show_explain_request
   
   /* Query that we've got SHOW EXPLAIN for */
   String query_str;
-
-  static void get_explain_data(void *arg);
+  
+  /* Overloaded virtual function */
+  void call_in_target_thread();
 };
 
 class THD;

sql/sql_show.cc

@@ -2065,9 +2065,7 @@ void mysqld_show_explain(THD *thd, ulong thread_id)
     explain_req.failed_to_produce= FALSE;
     
     /* Ok, we have a lock on target->LOCK_thd_data, can call: */
-    bres= tmp->apc_target.make_apc_call(Show_explain_request::get_explain_data,
-                                        (void*)&explain_req,
-                                        timeout_sec, &timed_out);
+    bres= tmp->apc_target.make_apc_call(&explain_req, timeout_sec, &timed_out);
 
     if (bres || explain_req.failed_to_produce)
     {